2.4 Monitoring Faults



Vocabulary


Creep meters: measures the movement along a strike slip fault
Laser ranging devices: device that measures changes with a laser beam and a reflector
Tiltmeters: measures tilting of the ground, works like a carpenter's level
Satellite moniter: uses radar to take picture of faults

Outline



Device that Monitor Faults

  • there are four different types of instruments
  • creep meters
    • a creep meter uses a wire stretched across a fault to measure horizontal movement of the ground
    • on one side of the ground, the wire is tied to the pole
    • on the other side of the ground, the wire is attached to a weight that can slide if the fault moves
    • geologists can measure how much the fault has moved because of the weight
  • laser-ranging devices
    • this device uses a laser beam to find tiny fault movements
    • this device can find any change in the distance to the reflector
  • tiltmeters
    • this instrument measures tilting of the ground
    • seismologists use this to consist of two bulbs that are filled with liquid and connected to a hollow stem
    • if the land rises, the liquid will go from one bulb to the other bulb
    • each bulb has a scale to measure the depth of the liquid
    • geologists read the scales to measure how much the fault has moved
  • satellite monitors
    • the satellite bounces radio waves off the ground
      • as the waves echo back into space, the satellite records them
    • the distance from the ground to the satellite changes, depends when the ground moves
      • these changes in elevation result when stress deforms the ground along the fault

Monitoring Risks in the United States

    • geologists can't predict earthquakes
    • the major earthquakes is the area of the pacific

Diagram



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